Charles a



(No'Model.)

@SMITH av T, P. TAYLOR.

TELEGRAPHY.

Patented' Septl 4,1883.

0 Mw T fs, wm 0 WL tnesses 1 I @WM f/@ GERRITT sMrTH, oF ASTORIA,

`'ITED STATES AND THEODORE F. TAYLOR, OF BROOKLYN,

NEW YORK.

TELEGRAPHY.

. SPECIFICATION forming pere ef Letters Patent NeQfaegces, aerea september 4, 1883.

Appneecen inea May 19, 1382. (Nemen.)

To a/ZZ wir/omit may concern:

Be it known that we, GERRITT SMITH and 'IHnononn F. TAYLOR, citizens of the United States, residing, respectively, in Astoria, in

the county of Queens, and in Brooklyn, inthe county of Kings, both iny the `State of New York, have invented certain new'` and useful y Improvements in Duplex Telegraphy, of which the following is a specification.

`In transmitting two o r more sets of signals simultaneouslyin opposite directions over one and the same telegraphic conductor, according to the method heretofore usually practiced, much interference and confusion arises from false signals which .are produced upon the receiving-instrument by currents of charge and discharge, the origin of `which is due to the electro-static or inductive capacity ofthe line. This phenomenon manifests itself in a marked manner when the line is of consideri able length and is welll insulated, and underapplianceseither for neutralizing the electro static charge upon the line-wire, or for counteracting its effect by artificially inducing a charge at the terminal station, and causingthis nto act simultaneously, but in an opposite sense,

upon the receiving-instrument. Y

Our invention differs in its general character from others hereinbefore referred to, in that we employ the electrostatic charge, instead of the dynamic current, as a means for operating the receiving-instrument, thereby utilizing the inductive capacity of the line as the active agent for the transmission of signals.

To this end ourinventionrconsista essentially, in the employment, in connection with any suitable apparatusffor duplex or multiple telegraphy, of ar condenser of considerable electro-static capacity interposed between the junction-of the main and articial lines and Vconnected to` the earth at G.: A wire, l, exy tends from the lever ofthe key K to the point '.transmittingbattery. By reason of this organization both the main .and artificial linesv `are wholly insulated from the earth at each 6o terminal station, and we are enabledto transmit the necessary signals in both directions by merely altering the distribution of the electrostatic charge in the system.

The accompanying drawing is a theoretical diagram illustrating a duplex telegraph arranged for simultaneous transmission from both terminal stations. y

Referring to the figure, K represents the n transmitting-key at one terminal station. We 7o prefer to make use of a double-current key, which transmits a current of one polarity when it is depressed and of the opposite polarity i when itis raised. This result may be effected by means of any one Vof a number of devices. 7 5 We have illustrated a simple form, in which two independent batteries, E and E2, of equal electro-motive force, but opposite polarity, are permanently connected, respectively, with the front and rear contacts of the key, the op- 8o posite poles of the batteries being united and connected to one terminal `of a condenser, C,

having a capacity approximately equal to that of the line L, the other terminal of which is 90 stat al to the point 4, where it unites with the articial` line A.

The receiving-instrument M, which may be an electro-magnetic, electrochemical, or other well-known and suitable apparatus for the purpose, is shown as placed in a bridge-wire, 3 4, between the main and artificial-lines, whereby it is rendered neutral to outgoing impulses; or,`as a well-known substitutefor this arrangement, the bridge-wire 3 4 may be dispensed Ioo with and a differential electro-magnetic receiving-instrument may be employed, the oppos- -ing coils of which are respectively included in the wires 2 3 and 2 4, having the same relation thereto as the-rheostats Z and ain the figure.

The artificial line A consists, essentially, of a rheostat, between which and the point 5 an equating-condenser (of a capacity which may be much less than that of the main line L) is interposed. Itis preferred to construct this rheostat in two or more sections, as shown at r', r2, and r3 in the figure, these being united in multiple arc to the conductor leading from the main line at 2. Between each rheostatsection and the opposite terminal, 5, of the artiflcial line a section of the condenser is interl posed, as shown at c', c2, and ci.

The effect of employing a sectional rheostat and sectional condenser is the same as if a single rheostat and single condenser of equal caf pacity were used; but the division into sections in the manner shown enables them tol be more conveniently and accurately adjusted'for the purpose of rendering the electrostatic capacity and time of charge and discharge of the artificial line the same as that of the main line.

The terminal section at the opposite end of the line L has its apparatus arrangedin precisely the same manner as that already described. v

It will be obvious from an inspection of the diagram that the main line and the artificial line at each station are electrically insulated from the earth by the interposition of the condensers, and hence the transmission of signals may be effected simply by varying the distribution of the electrostatic charge of the main and artificial lines and ofthe condensers attached thereto or forming a part thereof, the

office of the latter being not only toincrease the normal electro-static capacity of the line, thereby increasing the strength of the electrostatic impulses, but also to govern the distribution of the total electro-static charge.

The operation of the apparatusis as follows: When the key K is depressed, in order to transmit a signal, a positive charge from the battery E passes over the wire l (which virtually forms a portion of the main line).to.the point 2, where it divides, one portion going through the rheostat Z and mainline L to the condensers C c4 c5 c6 at the distant station. The receiving-instrument M 'at the home sta` tion,'being placed, as hereinbefore eXplained i'n the bridge-wire 3 4, or otherwise arranged so as to be rendered neutral toy outgoing im.- pulses, is not affected thereby; but at the distant station that portion of the charge whichA enters the condensers 0*, c5, and ci passes .through the receiving-instrument Mandproduces. a momentary positive signal. If, now, the key Kwbe raised, a negative impulse from the bat- .tery E2 is transmitted over the line in. like manner, and produces a momentary negative l positive or negative, are only momentary, yet

if a suitable receiving-instrument-such as the well-known polarized relay--be employed, the armature, having been thrown into one position by a positive impulse, will remain there until thrown back again by a negative impulse,

hence the signals of the ordinary Morse code may be transmitted in this manner without difficulty, as the action ofthe receiving-instrument will be the same as if prolonged electrodynamic currents were employed.

The combined resistance of the rheostats r',

r2, andof, constituting the essential portion of 8 5 the artificial line A, should be approximately equal tothe resistance of the line L; but the condensersc c2 c3 may be of correspondingly less capacity. It isadvantageous in most eases tov construct the said rheostats of unequal. resistances, so that the total resistance of the artificial line may be more conveniently adjusted to. correspond with the variable resist- .ance of the main line L, which in turn de pends upon conditions of insulation, due to changes. in thev weather, Src.

Our improved system is particularly well adapted for rapid automatic telegraphy, and when used for this purpose an automatic transmitter of any suitable character-such, for instance, as a patternstrip perforated with two rows of holes-is substituted for the key K, and a corresponding electro-chemical or other receiver is placed at M. The principle of operation is precisely the same as that hereinbefore explained.

We claim as our invention.-

l.l The combination, substantially as hereinbefore set forth, with a main line, of a battery and key at the home station, a condenser an. artificial line having one of its terminals .I OO

IIO

united with the main line and the other with Y the line terminal of said condenser, thus spanning said keyl and battery, and a condenser interposed in said artificial line.

2. The combination, substantially ashereinbefore set forth, with a main line, of a battery and key at the home station, a condenser interposed between said battery and the earth, an artificial line having 011e of its terminals united with the main line and the other with the line-terminal of said condenser, `an equating-condenser interposed in said artificial. line, and a receiving-instrument placed in'. such a relation to the main and artificial lines asto be rendered neutral to 'outgoing electrical impulses.

3. The combination, substantially as-here,

inbefore set forth, with a main line, of a bat-l tery and keyvat the home station, a condenser interposed between said battery and the earth,

an artificial line having one of its terminals In testimony whereof we have hereunto subunited with the main line and the otherwith scribed our names this 16th day of May, A. D. 1o l the line-terminal of said condenser, thus span- 1882.

ning said key and battery, an equating-con GERRITT SMITH. i 5 denser interposed in said artificial line, and a THEODORE F. TAYLOR. Ff Q u receiving-instrument interposed betweenasee- Witnesses: l ond condenser and the main line et the distant CHARLES A. TERRY, station. i MILLER C. EARL. 

